U.S. patent application number 14/576510 was filed with the patent office on 2015-04-16 for ink composition.
This patent application is currently assigned to OCE-TECHNOLOGIES B.V.. The applicant listed for this patent is OCE-TECHNOLOGIES B.V.. Invention is credited to Roelof H. EVERHARDUS, Antonius P.M.M. VAN ROY, Michael T.J. VERHEGGEN.
Application Number | 20150105504 14/576510 |
Document ID | / |
Family ID | 48672571 |
Filed Date | 2015-04-16 |
United States Patent
Application |
20150105504 |
Kind Code |
A1 |
VERHEGGEN; Michael T.J. ; et
al. |
April 16, 2015 |
INK COMPOSITION
Abstract
Disclosed is an aqueous ink composition including between 1 and
40 weight % of a water dispersible resin, between 0.5 and 15 weight
% of a colorant, between 20 and 80 weight % of water and between 1
and 30 weight % of an acetal cosolvent, wherein all amounts are
relative to the total ink composition. The ink composition may
further include between 15 and 75 weight % of a dispersion
stabilizing cosolvent.
Inventors: |
VERHEGGEN; Michael T.J.;
(Weert, NL) ; EVERHARDUS; Roelof H.; (Lomm,
NL) ; VAN ROY; Antonius P.M.M.; (Grashoek,
NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OCE-TECHNOLOGIES B.V. |
Venlo |
|
NL |
|
|
Assignee: |
OCE-TECHNOLOGIES B.V.
Venlo
NL
|
Family ID: |
48672571 |
Appl. No.: |
14/576510 |
Filed: |
December 19, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2013/061650 |
Jun 6, 2013 |
|
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14576510 |
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Current U.S.
Class: |
524/108 ;
524/378 |
Current CPC
Class: |
C09D 11/38 20130101;
C09D 11/10 20130101; C09D 11/033 20130101; C09D 11/107 20130101;
C09D 11/30 20130101 |
Class at
Publication: |
524/108 ;
524/378 |
International
Class: |
C09D 11/033 20060101
C09D011/033; C09D 11/107 20060101 C09D011/107; C09D 11/30 20060101
C09D011/30 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2012 |
EP |
12172763.0 |
Claims
1. Ink composition comprising: 1-40 weight % of a latex resin;
0.5-15 weight % of a colorant; 20-80 weight % of water; and 1-30
weight % of an acetal cosolvent; wherein all amounts are relative
to the total ink composition.
2. The ink composition according to claim 1, wherein the acetal
cosolvent is selected from the group consisting of glycerol formal,
alkyl acetals and diether acetals.
3. The ink composition according to claim 1, wherein the acetal
cosolvent is a linear diether acetal.
4. The ink composition according to claim 1, wherein the acetal
cosolvent has a molecular structure in accordance with Formula 1
R.sub.1--O--R.sub.2--O--CH.sub.2--O--R.sub.3--O--R.sub.4 Formula 1
wherein: R.sub.1 and R.sub.4 are independently of one another
selected from the group consisting of --H, and C.sub.1-C.sub.6
monovalent alkyl groups; R.sub.2 and R.sub.3 are independently of
one another selected from the group consisting of C.sub.2-C.sub.6
alkyl divalent groups.
5. The ink composition according to claim 4, wherein: R.sub.1 and
R.sub.4 are independently of one another selected from the group
consisting of --H, --CH.sub.3, --C.sub.2H.sub.5, and
--C.sub.3H.sub.7.
6. The ink composition according to claim 4, wherein: R.sub.2 and
R.sub.3 are independently of one another selected from the group
consisting of --C.sub.2H.sub.4--, --C.sub.3H.sub.6, and
--C.sub.4H.sub.8--.
7. The ink composition according to claim 1, wherein the acetal
cosolvent is Bis(2-methoxy-ethoxy)methane.
8. The ink composition according to claim 1, wherein the colorant
is a dye, a pigment, a mixture of dyes, a mixture of pigments or a
mixture of pigments and dyes.
9. The ink composition according to claim 1, wherein the latex
resin is selected from the group consisting of: polyester resins,
polyurethane resins, polyepoxy resins, polyamide resins, polyether
resins, poly(meth)acrylic resins, acryl-silicone resins,
fluorine-based resins, polyolefin resins, polystyrene-based resins,
polybutadiene-based resins, polyvinyl acetate-based resins,
polyvinyl alcohol-based resins, polyvinyl ester-based resins,
polyvinyl chloride-based resins, polyacrylic acid-based resins,
unsaturated carboxylic acid-based resins, copolymer resins and
combinations of the plural.
10. The ink composition according to claim 1, further comprising
15-75 weight % of a dispersion stabilizing cosolvent.
11. The ink composition according to claim 10, wherein said
dispersion stabilizing cosolvent is a water soluble organic solvent
selected from the group consisting of: polyhydric alcohols,
polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers,
nitrogen-containing heterocyclic compounds, amides, amines,
ammonium compounds, sulfur-containing compounds, propylene
carbonate, ethylene carbonate and a combination of the plural.
12. The ink composition according to claim 1, further comprising a
surfactant in an amount of between 0.01 weight % and 3 weight %
relative to the total ink composition.
13. The ink composition according to claim 1, wherein the acetal
cosolvent is selected from the group consisting of:
glycerol-formal; Bis(2-methoxy-ethoxy)methane; alkyl-acetals and a
combination of the plural
14. The ink composition according to claim 1, wherein the acetal
cosolvent is selected from the group consisting of: glycerol-formal
and Bis(2-methoxy-ethoxy)methane, and wherein the acetal cosolvent
is present in an amount of between 1 weight % and 20 weight %,
relative to the total ink composition.
15. The ink composition according to claim 1, wherein the acetal
cosolvent is an alkyl-acetal, which alkyl-acetal is at least one
selected from the group consisting of: methylal, ethylal and
butylal.
16. The ink composition according to claim 15, wherein the
alkyl-acetal is present in an amount of between 1 weight % and 10
weight % relative to the total ink composition.
17. The ink composition according to claim 9, wherein the latex
resin is at least one selected from the group consisting of a
styrene-acrylate copolymer resin, and a styrene-butadiene copolymer
resin.
Description
[0001] This application is a Continuation of PCT International
Application No. PCT/EP2013/061650, filed on Jun. 6, 2013, which
claims priority under 35 U.S.C. 119(a) to Patent Application No.
12172763.0, filed in Europe on Jun. 20, 2012, all of which are
hereby expressly incorporated by reference into the present
application.
FIELD OF THE INVENTION
[0002] The present invention relates to an ink composition,
suitable for use in an inkjet printing process.
BACKGROUND ART
[0003] EP 2 233 309 A2 discloses an ink composition containing
water in an amount of 20-90 weight % based on the total weight of
the ink, a pigment and a resin, which may be a water dispersed
resin (i.e., a latex). WO 2011/021591 discloses an inkjet ink
containing a water-dispersible colorant, a water-soluble organic
solvent, a surfactant, a penetrant, water and preferably a water
dispersible resin. Both mentioned prior art documents disclose
methods for printing said inks onto media normally used in process
printing or offset printing (e.g., machine coated (MC) or off-set
coated media).
[0004] In a highly productive inkjet printing it is preferred to
obtain (almost) instantly dry and robust prints, which can be
handled at high speed and stay undamaged during transport from a
printing module to further process equipment, for example to a
fuser station in the printer.
[0005] A disadvantage, of known aqueous ink compositions is that
they exhibit too low of a drying speed and/or require relatively
high fuse energies to be suitably used in a highly productive
inkjet printing process.
[0006] A disadvantage of known aqueous ink compositions comprising
dispersed components (e.g., a dispersed resin and/or dispersed dyes
or pigments) is that such ink compositions, in particular when used
in highly productive inkjet printing, need to contain a substantial
non-evaporating or hardly evaporating dispersion-stabilizing polar
fraction (e.g., 20 weight % or more relative to the total ink
composition) of water soluble organic cosolvents, usually aliphatic
polyhydric alcohols having a relatively low vapor pressure to
provide reliable jetting and cleaning behavior of the inkjet
printing devices (print heads). Such a non-evaporating or hardly
evaporating dispersion-stabilizing polar fraction may, depending on
the nature of the medium to be printed on, have a negative
influence on the drying speed of a print and/or the required fuse
energy. It may therefore be beneficial to print quality and
robustness to provide an ink composition having a more specific
drying and/or fuse behavior. In particular, when intended to be
used in a highly productive inkjet printing process, an ink
composition having a higher drying speed and relatively low
required fuse energy is preferred.
[0007] Alkylene or dialkylene glycol mono- and di-ethers (e.g.,
propylene glycol mono-methyl ether) are commonly used as a
cosolvent in the ink formulations to tune the drying behavior,
sometimes in combination with heating (.about.50.degree. C.) of the
medium during printing. However, the choice of suitable cosolvents
from this class of glycol ethers is limited, partly because of high
HS&E (i.e., Health, Safety and Environmental) risks.
[0008] It is therefore an object of the present invention to
provide an aqueous ink composition having an improved drying and
fuse behavior, without compromising the print quality and print
robustness to an unacceptable extent.
[0009] It is another object of the present invention to provide an
aqueous ink composition comprising dispersed components and having
an improved drying and fuse behavior, without compromising the
dispersion stability of the ink composition and the print quality
and print robustness to an unacceptable extent.
[0010] It is yet another object of the present invention to provide
an aqueous ink composition with low and in particular negligible
HS&E risks.
SUMMARY OF THE INVENTION
[0011] These objects are at least partly achieved by providing an
ink composition comprising: [0012] 1-40 weight % of a water
dispersible resin; [0013] 0.5-15 weight % of a colorant; [0014]
20-80 weight % water; [0015] 1-30 weight % of an acetal cosolvent;
wherein all amounts are relative to the total ink composition.
[0016] A water dispersible resin may be added to the ink
composition as a stable dispersion of the water dispersible resin
in water. The stable dispersion of the water dispersible resin in
water may also be termed a latex composition. An ink composition
comprising a water dispersed resin may be termed a latex ink
composition.
[0017] The colorant may be a dye, a pigment, a mixture of dyes, a
mixture of pigments or a mixture of pigments and dyes. Preferably,
the colorant comprises a water-dispersible colorant, more
preferably, a water-dispersible pigment.
[0018] An acetal is a compound of which the molecules comprise two
single-bonded oxygen atoms attached to the same carbon atom.
[0019] Inventors have surprisingly found that the class of acetal
cosolvents, characterized by their compatibility with water
comprised in the ink composition, are capable of significantly
improving the drying and fuse behavior of the ink composition on a
wide range of media, in particular, on hardly or non absorbing
media such as machine coated (MC) media, without substantially
compromising the print quality. The ink compositions according to
the present invention may provide improved instant dryness and
robustness of the prints.
[0020] Without wanting to be bound to any theory, it is thought
that, depending on the chemical structure, the acetals may function
as a penetrant (into absorbing media), or as an evaporation
accelerator of water (via weakened Hydrogen bonding or azeotrope
with water), or a combination of both.
[0021] Media-types intended to be printed on are the well-absorbing
plain papers and inkjet coated media but also the slowly absorbing
offset-coated media (also termed machine coated (MC) media) and
even non-absorbing media such as films of PE, PP, PET, PVC or
composites or mixtures thereof.
[0022] One characteristic of the use of a suitable acetal cosolvent
is a faster (semi-dry) film formation of aqueous ink compositions,
in particular aqueous pigmented latex ink compositions on the
mentioned media, by a more complete and/or faster water removal by
absorption and/or evaporation, already at ambient temperatures.
[0023] A potential additional advantage of acetal cosolvents is
that they are in general eco-friendly co-solvents which are partly
bio-based (i.e., may be derived from bio-feedstocks).
[0024] Latex ink compositions contain a water dispersed resin,
which may primarily be used to improve the robustness of the
printed image on a recording substrate. In order to provide an
improved robustness to the printed image, the latex composition
comprised in the ink composition must be able to form a film on the
recording substrate. Therefore, the ink composition and in
particular the latex composition must have a minimal film-forming
temperature (MFFT) of below the temperature of the recording
substrate during printing. It is therefore preferable to use latex
compositions having a low, e.g., room temperature, MFFT. One
potential disadvantage of this is that film formation might occur
at the jetting temperature inside the inkjet printing device, in
particular inside the nozzle orifices of the inkjet printing
device, which may lead to clogging of the nozzle orifices and hence
to a disturbance of the jetting process. For this reason a latex
composition having an MFFT of above the jetting temperature is
preferred.
[0025] One potential disadvantage of such a latex inkjet ink is
that film formation on the recording substrate may need to be
induced and/or assisted by heating the printed recording substrate.
Thus, in general, by selecting and using a latex composition with a
higher MFFT in an ink composition for improving the stability in
the inkjet printing device, the energy consumption to fix (i.e., to
fuse) the ink composition on the recording substrate increases. A
separate fuser station may be required, which operates at elevated
temperatures (above the MFFT of the ink composition) to obtain a
desired robustness of the prints.
[0026] An ink composition according to the one embodiment
containing a water dispersible resin and an acetal cosolvent may
show an improved drying behavior and a reduced energy consumption
for fixing (fusing) the ink to the recording substrate.
[0027] In an embodiment, the MFFT of the latex composition is above
the jetting temperature, in particular above 30.degree. C.,
preferably between 35.degree. C. and 95.degree. C., more preferably
between 40.degree. C. and 90.degree. C.
[0028] In an embodiment, the water-dispersible resin has a glass
transition temperature (T.sub.g) of above 30.degree. C., preferably
between 50.degree. C. and 120.degree. C., more preferably between
60.degree. C. and 100.degree. C. The T.sub.g of the water
dispersible resin determines the MFFT of the latex composition to a
large extent. In general, the higher the T.sub.g of the dispersed
resin is, the higher the MFFT of the latex composition will be.
However, in the presence of an acetal cosolvent according to the
present invention, the MFFT of the latex composition comprising a
resin having a relatively high T.sub.g may be significantly
reduced. A potential advantage of this is that film formation and
fusing the printed image to the recording substrate may occur at
relatively mild temperature conditions, thus showing reduced energy
consumption, while the robustness of the print is not substantially
compromised.
[0029] Without wanting to be bound to any theory, it is believed
that besides the absorption and/or evaporation enhancing effect as
described above, the acetal cosolvent may function as a plasticizer
for the water-dispersible resin to a certain extent. The
plasticizing effect results in a decrease of the MFFT of the latex
composition comprising a water dispersible resin having a
relatively high T.sub.g (e.g., above 70.degree. C.) and hence in a
reduced energy consumption for fixing (fusing) the ink to the
recording substrate. Once the ink has been fixed to the recording
substrate there is no significant difference in robustness compared
to an ink composition comprising a water dispersible resin having a
similar T.sub.g in the absence of the acetal cosolvent.
[0030] In an embodiment, the ink composition comprises 1-75 weight
% of an additional cosolvent, preferably a dispersion stabilizing
cosolvent, in particular a water soluble organic solvent.
[0031] In such embodiment, the dispersion stabilizing cosolvent and
the acetal cosolvent are selected such that both are compatible
with water and with each other.
[0032] In an embodiment, the ink composition comprises a surfactant
in an amount of between 0.01 weight % and 3 weight % relative to
the total ink composition.
[0033] One or more surfactants may be added to an ink composition
to tune the surface tension of the ink composition in order to
improve the jet stability and/or the wettability of the surface of
a recording medium. Improved wettability may improve spreading of
an ink droplet on the surface of an image receiving substrate which
may result in an improved image density and color saturation of the
image formed and may reduce white spots in the printed image.
[0034] In an embodiment, the acetal cosolvent is selected from the
group consisting of: glycerol-formal (i.e. a mixture of
5-hydroxy-1,3-dioxane and 4-hydroxymethyl-1,3-dioxolane);
Bis(2-methoxy-ethoxy)methane (also termed:
2,5,7,10-Tetra-oxa-undecane: TOU); 1,3-dioxolane; alkyl-acetals and
a combination of the plural.
[0035] In an embodiment, glycerol-formal;
Bis(2-methoxy-ethoxy)methane (2,5,7,10-Tetra-oxa-undecane: TOU) and
1,3-dioxolane are preferably present in an amount of between 1
weight % and 20 weight %, preferably between 2 weight % and 15
weight %, more preferably between 3 weight % and 10 weight %
relative to the total ink composition.
[0036] In an embodiment, 1,3-dioxolane is preferably present in an
amount of between 1 weight % and 10 weight %, preferably between 2
weight % and 10 weight %, more preferably between 3 weight % and 8
weight % relative to the total ink composition.
[0037] In an embodiment, the acetal cosolvent may be an
alkyl-acetal selected from the group consisting of: methylal,
ethylal and butylal. The alkyl-acetal may be present in an amount
of between 1 weight % and 10 weight %, preferably between 3 weight
% and 10 weight %, more preferably between 5 weight % and 8 weight
% relative to the total ink composition.
[0038] In an embodiment, the acetal cosolvent is an ether acetal,
preferably a diether acetal.
[0039] In an embodiment, the acetal cosolvent is a linear ether
acetal or a linear diether acetal.
[0040] In an embodiment, the acetal cosolvent has a molecular
structure in accordance with Formula 1
R.sub.1--O--R.sub.2--O--CH.sub.2--O--R.sub.3--O--R.sub.4 Formula
1
wherein: R.sub.1 and R.sub.4 are independently of one another
selected from the group consisting of --H, C.sub.1-C.sub.6
monovalent alkyl groups, which may be branched or linear, in
particular --CH.sub.3, --C.sub.2H.sub.6, and --C.sub.3H.sub.7;
R.sub.2 and R.sub.3 are independently of one another selected from
the group consisting of C.sub.2-C.sub.6 alkyl divalent groups,
which may be branched or linear, in particular --C.sub.2H.sub.4--,
--C.sub.3H.sub.6, --C.sub.4H.sub.8--.
[0041] In an embodiment, the acetal cosolvent is
Bis(2-methoxy-ethoxy)methane (also termed:
2,5,7,10-Tetra-oxa-undecane: TOU).
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The present invention will become more fully understood from
the detailed description given herein below and accompanying
schematical drawings which are given by way of illustration only
and are not limitative of the invention, and wherein:
[0043] FIG. 1 shows a schematic representation of an inkjet
printing system.
[0044] FIGS. 2A and 2B show schematic representations of an
assembly of inkjet heads.
[0045] FIG. 3 shows a correlation between the Ricoh fuser settings
and the rotational speed of the fuse drum incorporated in such a
fuser.
DETAILED DESCRIPTION
Ink Composition
[0046] An ink composition according to the present invention
comprises a solvent, in particular water; a colorant, preferably a
water-dispersible colorant, a water-dispersible resin and an acetal
cosolvent. The ink composition may optionally comprise an
additional cosolvent, preferably at least one dispersion
stabilizing cosolvent. In the context of the present invention the
term cosolvent should be interpreted broadly: a cosolvent may
comprise liquid cosolvents and/or water soluble (solid) compounds,
in particular, water soluble (solid) compounds having a dispersion
stabilizing effect when solved in water. The ink composition may
further comprise a surfactant and optionally other additives. The
components of the inks will be described in detail in the next
sections.
Solvent
[0047] Water is cited as an environmentally friendly and hence
desirable solvent. In the present invention, the content of water
to the whole ink is preferably from 20 weight % to 80 weight %. It
is more preferable that the content of water is from 30 weight % to
75 weight %, even more preferable from 40 weight % to 70 weight
%.
Colorant
[0048] In the inkjet ink according to the present invention, a
colorant, preferably a water-dispersible colorant, is present. The
colorant may be a dye, a pigment, a mixture of dyes, a mixture of
pigments or a mixture of pigments and dyes. A pigment (preferably
water dispersible) may be primarily used as a water-dispersible
colorant in view of the weatherability, and, for the purpose of
controlling color tone; a dye may be contained within the range not
impairing the weatherability. The pigment is not particularly
limited and may be suitably selected in accordance with the
intended use.
[0049] Examples of the pigment usable in the present invention
include those commonly known without any limitation. For example,
an organic pigment such as an insoluble pigment or a lake pigment,
as well as an inorganic pigment such as carbon black, may be
used.
[0050] Examples of the insoluble pigments are not particularly
limited, but preferred are an azo, azomethine, methine,
diphenylmethane, triphenylmethane, quinacridone, anthraquinone,
perylene, indigo, quinophthalone, isoindolinone, isoindoline,
azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, or
diketopyrrolopyrrole dye.
[0051] For example, inorganic pigments and organic pigments for
black and color inks are exemplified. These pigments may be used
alone or in combination.
[0052] As the inorganic pigments, it is possible to use carbon
blacks produced by a known method such as a contact method, furnace
method and thermal method, in addition to titanium oxide, iron
oxide, calcium carbonate, barium sulfate, aluminum hydroxide,
barium yellow, cadmium red and chrome yellow.
[0053] As the organic pigments, it is possible to use azo pigments
(including azo lake, insoluble azo pigments, condensed pigments,
chelate azo pigments and the like), polycyclic pigments (e.g.,
phthalocyanine pigments, perylene pigments, perynone pigments,
anthraquinone pigments, quinacridone pigments, dioxazine pigments,
indigo pigments, thioindigo pigments, isoindolinone pigments, and
quinophthalone pigments), dye chelates (e.g., basic dye type
chelates, and acidic dye type chelates), nitro pigments, nitroso
pigments, aniline black. Among these, particularly, pigments having
high affinity with water are preferably used.
[0054] Specific pigments which are preferably usable are listed
below.
[0055] Examples of pigments for magenta or red include: C.I.
Pigment Red 1, C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment
Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 15,
C.I. Pigment Red 16, C.I. Pigment Red 17, C.I. Pigment Red 22, C.I.
Pigment Red 23, C.I. Pigment Red 31, C.I. Pigment Red 38, C.I.
Pigment Red 48:1, C.I. Pigment Red 48:2 (Permanent Red 2B(Ca)),
C.I. Pigment Red 48:3, C.I. Pigment Red 48:4, C.I. Pigment Red
49:1, C.I. Pigment Red 52:2; C.I. Pigment Red 53:1, C.I. Pigment
Red 57:1 (Brilliant Carmine 6B), C.I. Pigment Red 60:1, C.I.
Pigment Red 63:1, C.I. Pigment Red 64:1, C.I. Pigment Red 81. C.I.
Pigment Red 83, C.I. Pigment Red 88, C.I. Pigment Red
101(colcothar), C.I. Pigment Red 104, C.I. Pigment Red 106, C.I.
Pigment Red 108 (Cadmium Red), C.I. Pigment Red 112, C.I. Pigment
Red 114, C.I. Pigment Red 122 (Quinacridone Magenta), C.I. Pigment
Red 123, C.I. Pigment Red 139, C.I. Pigment Red 44, C.I. Pigment
Red 146, C.I. Pigment Red 149, C.I. Pigment Red 166, C.I. Pigment
Red 168, C.I. Pigment Red 170, C.I. Pigment Red 172, C.I. Pigment
Red 177, C.I. Pigment Red 178, C.I. Pigment Red 179, C.I. Pigment
Red 185, C.I. Pigment Red 190, C.I. Pigment Red 193, C.I. Pigment
Red 209, C.I. Pigment Red 219 and C.I. Pigment Red 222, C.I.
Pigment Violet 1 (Rhodamine Lake), C.I. Pigment Violet 3, C.I.
Pigment Violet 5:1, C.I. Pigment Violet 16, C.I. Pigment Violet 19,
C.I. Pigment Violet 23 and C.I. Pigment Violet 38.
[0056] Examples of pigments for orange or yellow include: C.I.
Pigment Yellow 1, C.I. Pigment Yellow 3, C.I. Pigment Yellow 12,
C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow
15, C.I. Pigment Yellow 15:3, C.I. Pigment Yellow 17, C.I. Pigment
Yellow 24, C.I. Pigment Yellow 34, C.I. Pigment Yellow 35, C.I.
Pigment Yellow 37, C.I. Pigment Yellow 42 (yellow iron oxides),
C.I. Pigment Yellow 53, C.I. Pigment Yellow 55, C.I. Pigment Yellow
74, C.I. Pigment Yellow 81, C.I. Pigment Yellow 83, C.I. Pigment
Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 95, C.I.
Pigment Yellow 97, C.I. Pigment Yellow 98, C.I. Pigment Yellow 100,
C.I. Pigment Yellow 101, C.I. Pigment Yellow 104, C.I. Pigment
Yellow 408, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I.
Pigment Yellow 117, C.I. Pigment Yellow 120, C.I. Pigment Yellow
128, C.I. Pigment Yellow 138, C.I. Pigment Yellow 150, C.I. Pigment
Yellow 151, C.I. Pigment Yellow 153 and C.I. Pigment Yellow 183;
C.I. Pigment Orange 5, C.I. Pigment Orange 13, C.I. Pigment Orange
16, C.I. Pigment Orange 17, C.I. Pigment Orange 31, C.I. Pigment
Orange 34, C.I. Pigment Orange 36, C.I. Pigment Orange 43, and C.I.
Pigment Orange 51.
[0057] Examples of pigments for green or cyan include: C.I. Pigment
Blue 1, C.I. Pigment Blue 2, C.I. Pigment Blue 15, C.I. Pigment
Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3
(Phthalocyanine Blue), C.I. Pigment Blue 16, C.I. Pigment Blue
17:1, C.I. Pigment Blue 56, C.I. Pigment Blue 60, C.I. Pigment Blue
63, C.I. Pigment Green 1, C.I. Pigment Green 4, C.I. Pigment Green
7, C.I. Pigment Green 8, C.I. Pigment Green 10, C.I. Pigment Green
17, C.I. Pigment Green 18 and C.I. Pigment Green 36.
[0058] Further, examples of pigments for black include: C.I.
Pigment Black 1, C.I. Pigment Black 6, C.I. Pigment Black 7 and
C.I. Pigment Black 11. Specific examples of pigments for black
color ink usable in the present invention include carbon blacks
(e.g., furnace black, lamp black, acetylene black, and channel
black); (C.I. Pigment Black 7) or metal-based pigments (e.g.,
copper, iron (C.I. Pigment Black 11), and titanium oxide; and
organic pigments (e.g., aniline black (C.I. Pigment Black 1).
[0059] The average particle diameter (D50) of the water-dispersible
pigment is preferably from 0.01 .mu.m (10 nm) to 0.25 .mu.m (250
nm), more preferably from 20 nm to 200 nm, and it is still more
preferably from 40 nm to 150 nm in the inkjet ink in view of the
dispersion stability and ejection reliability.
[0060] The amount of the water-insoluble pigment contained in the
inkjet ink, as a solid content, is preferably 0.5 weight % to 15
weight % based on the total weight of the ink, more preferably 0.8
weight % to 10 weight %, and even more preferably between 1 weight
% and 6 weight %. When the amount of the water-insoluble pigment is
less than 0.5 weight %, the color developing ability and image
density of the ink may degrade. When it is more than 15 weight %,
unfavorably, the viscosity of the ink may be increased, causing
degradation in ink ejection stability.
Water Dispersible Resin (Latex Resin)
[0061] The inkjet ink according to the present invention contains a
water-dispersible resin in view of the pigment fixability to
recording media. As the water-dispersible resin, a
water-dispersible resin excellent in one or more of film
formability (image formability) and having one or more of high
water repellency, high waterfastness, and high weatherability is
useful in recording images having high waterfastness and high image
density (high color developing ability).
[0062] Examples of the water-dispersible resin include synthetic
resins and natural polymer compounds.
[0063] Examples of the synthetic resins include polyester resins,
polyurethane resins, polyepoxy resins, polyamide resins, polyether
resins, poly(meth)acrylic resins, acryl-silicone resins,
fluorine-based resins, polyolefin resins, polystyrene-based resins,
polybutadiene-based resins, polyvinyl acetate-based resins,
polyvinyl alcohol-based resins, polyvinyl ester-based resins,
polyvinyl chloride-based resins, polyacrylic acid-based resins,
unsaturated carboxylic acid-based resins and copolymers such as
styrene-acrylate copolymer resins, styrene-butadiene copolymer
resins, and combinations of the plural.
[0064] Examples of the natural polymer compounds include
celluloses, rosins, and natural rubbers.
[0065] Examples of commercially available water-dispersible resin
emulsions include: Joncryl 537 and 7640 (styrene-acrylic resin
emulsion, made by Johnson Polymer Co., Ltd.), Microgel E-1002 and
E-5002 (styrene-acrylic resin emulsion, made by Nippon. Paint Co.,
Ltd.), Voncoat 4001 (acrylic resin emulsion, made by Dainippon Ink
and Chemicals Co., Ltd.), Voncoat 5454 (styrene-acrylic resin
emulsion, made by Dainippon Ink and Chemicals Co., Ltd.), SAE-1014
(styrene-acrylic resin emulsion, made by Zeon Japan Co., Ltd.),
Jurymer ET-410 (acrylic resin emulsion, made by Nihon Junyaku Co.,
Ltd.), Aron HD-5 and A-104 (acrylic resin emulsion, made by Toa
Gosei Co., Ltd.), Saibinol SK-200 (acrylic resin emulsion, made by
Saiden Chemical Industry Co., Ltd.), and Zaikthene L (acrylic resin
emulsion, made by Sumitomo Seika Chemicals Co., Ltd.), acrylic
copolymer emulsions of DSM Neoresins, e.g. the NeoCryl product
line, in particular acrylic styrene copolymer emulsions NeoCryl
A-662, NeoCryl A-1131, NeoCryl A-2091, NeoCryl A-550, NeoCryl
BT-101, NeoCryl SR-270, NeoCryl XK-52, NeoCryl XK-39, NeoCryl
A-1044, NeoCryl A-1049, NeoCryl A-1110, NeoCryl A-1120, NeoCryl
A-1127, NeoCryl A-2092, NeoCryl A-2099, NeoCryl A-308, NeoCryl
A-45, NeoCryl A-615, NeoCryl BT-24, NeoCryl BT-26, NeoCryl BT-26,
NeoCryl XK-15, NeoCryl X-151, NeoCryl XK-232, NeoCryl XK-234,
NeoCryl XK-237, NeoCryl XK-238-NeoCryl XK-86, NeoCryl XK-90 and
NeoCryl XK-95. However, the water-dispersible resin emulsion is not
limited to these examples.
[0066] The water-dispersible resin may be used in the form of a
homopolymer, a copolymer or a composite resin, and all of
water-dispersible resins having a monophase structure or core-shell
structure and those prepared by power-feed emulsion polymerization
may be used.
[0067] The content of the water-dispersible resin added in the ink
of the present invention is preferably from 1-40 weight % based on
the total weight of the ink, and it is more preferably from 1.5-30
weight %, and it is still more preferably from 2-25 weight %. Even
more preferably, the amount of the water-dispersible resin
contained in the inkjet ink, as a solid content, is 2.5 weight % to
15 weight %, and more preferably 3 weight % to 7 weight %, relative
to the total ink composition.
[0068] The average particle diameter (D50) of the water-dispersible
resin is preferably from 10 nm-1 .mu.m, it is more preferably from
10-500 nm, and it is still more preferably from 20-200 nm, and
especially preferably it is from 50-200 nm. In addition, there are
no specific restrictions to the particle size distribution of the
polymer particles, and it is possible that the polymer particles
have a broad particle size distribution or the polymer particles
have a particle size distribution of monodisperse type.
[0069] In an embodiment, the ink composition according to the
present invention comprises two or more water-dispersible resins
selected from the above cited synthetic resins, synthetic copolymer
resins and natural polymer compounds in admixture with each
other.
Acetal Cosolvent
[0070] An ink composition according to the present invention
comprises an acetal cosolvent. Suitable examples of acetal
cosolvents are: glycerol-formal (i.e. a mixture of
5-hydroxy-1,3-dioxane and 4-hydroxymethyl-1,3-dioxolane);
Bis(2-methoxy-ethoxy)methane (also termed:
2,5,7,10-Tetra-oxa-undecane: TOU); 1,3-dioxolane; alkyl-acetals,
like methylal, ethylal and butylal.
[0071] The acetal cosolvents may be used alone or in a combination
of the plural.
[0072] Glycerol-formal; Bis(2-methoxy-ethoxy)methane
(2,5,7,10-Tetra-oxa-undecane: TOU) and 1,3-dioxolane are preferably
present in an amount of between 1 weight % and 20 weight %,
preferably between 2 weight % and 15 weight %, more preferably
between 3 weight % and 10 weight % relative to the total ink
composition.
[0073] 1,3-dioxolane is preferably present in an amount of between
1 weight % and 10 weight %, preferably between 2 weight % and 10
weight %, more preferably between 3 weight % and 8 weight %
relative to the total ink composition.
[0074] Alkyl-acetals like methylal, ethylal and butylal are
preferably present in an amount of between 1 weight % and 10 weight
%, preferably between 3 weight % and 10 weight %, more preferably
between 5 weight % and 8 weight % relative to the total ink
composition.
Optional Additional Cosolvent
[0075] As a solvent of the ink, for the purposes of improving the
ejection property of the ink or adjusting the ink physical
properties, the ink optionally, but preferably contains an
additional cosolvent, preferably a dispersion stabilizing
cosolvent, in particular a water soluble organic solvent in
addition to water. As long as the effect of the present invention
is not damaged, there is no restriction in particular in the type
of the water soluble organic solvent.
[0076] Examples of the water-soluble organic solvent include
polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric
alcohol aryl ethers, nitrogen-containing heterocyclic compounds,
amides, amines, ammonium compounds, sulfur-containing compounds,
propylene carbonate and ethylene carbonate.
[0077] Examples of the additional cosolvent include: glycerin (also
termed glycerol), propylene glycol, dipropylene glycol,
tripropylene glycol, tetrapropylene glycol, polypropylene glycol,
ethylene glycol, diethylene glycol, triethylene glycol,
tetraethylene glycol, polyethylene glycols preferably having a
molecular weight of between 200 gram/mol and 1000 gram/mol (e.g.
PEG 200, PEG 400, PEG 600, PEG 800, PEG 1000), glycerol ethoxylate,
petaerythritol ethoxylate, polyethylene glycol (di)methylethers
preferably having a molecular weight of between 200 gram/mol and
1000 gram/mol, tri-methylol-propane, diglycerol (diglycerin),
trimethylglycine (betaine), N-methylmorpholine N-oxide,
decaglyserol, 1,4-butanediol, 1,3-butanediol, 1,2,6-hexanetriol,
2-pyrrolidinone, dimethylimidazolidinone, ethylene glycol
mono-butyl ether, diethylene glycol monomethyl ether, diethylene
glycol monoethyl ether, diethylene glycol mono-propyl ether,
diethylene glycol mono-butyl ether, triethylene glycol monomethyl
ether, triethylene glycol monoethyl ether, triethylene glycol
mono-propyl ether, triethylene glycol mono-butyl ether,
tetraethylene glycol monomethyl ether, tetraethylene glycol
monoethyl ether, propylene glycol mono-butyl ether, dipropylene
glycol monomethyl ether, dipropylene glycol monoethyl ether,
dipropylene glycol monopropyl ether, diethylene glycol monobutyl
ether, tripropylene glycol monomethyl ether, tripropylene glycol
monoethyl ether, tripropylene glycol monopropyl ether, tripropylene
glycol monobutyl ether, tetrapropylene glycol monomethyl ether,
diethylene glycol diethyl ether, diethylene glycol dibutyl ether,
triethylene glycol diethyl ether, triethylene glycol dibutyl ether,
dipropylene glycol dibutyl ether, tri propylene glycol dibutyl
ether, 3-methyl 2,4-pentanediol, diethylene-glycol-monoethyl ether
acetate, 1,2-hexanediol, 1,2-pentanediol and 1,2-butanediol.
[0078] Specific examples of the polyhydric alcohols include
dipropylene glycol, 1,5-pentanediol, 3-methyl-1,3-butanediol,
propylene glycol, 2-methyl-2,4-pentanediol, ethylene glycol,
tripropylene glycol, hexylene glycol, polyethylene glycol,
polypropylene glycol, 1,6-hexanediol, 1,2,6-hexanetriol,
trimethylolethane and trimethylolpropane.
[0079] Examples of the polyhydric alcohol alkyl ethers include
ethylene glycol monoethylether, ethylene glycol monobutylether,
diethylene glycol monomethylether, diethylene glycol
monoethylether, diethylene glycol monobutylether, ethylene glycol
mono-2-ethylhexylether and propylene glycol monoethylether.
[0080] Examples of the polyhydric alcohol aryl ethers include
ethylene glycol monophenyl ether and ethylene glycol monobenzyl
ether.
[0081] Examples of the nitrogen-containing heterocyclic compounds
include 2-pyrrolidone, N-methyl-2-pyrrolidone,
1,3-dimethyl-2-imidazolidionone, .epsilon.-caprolactam, and
.gamma.-butyrolactone.
[0082] Examples of the amides include formamide, N-methylformamide,
N,N-dimethylformamide, and N,N-diethylformamide.
[0083] Examples of the amines include monoethanolamine,
dimethanolamine, triethanolamine, N,N-dimethylmonoethanolamine,
N-methyldiethanolamine, N-methylethanolamine, N-phenylethanolamine,
3-aminopropyl diethylamine, N-ethyldiethanolamine,
N,N-diethylmonoethanolamine, tripropanolamine,
2-amino-2-methyl-1-propanol, N-ethyl-monoethanolamine,
N,N-di-n-butylmonoethanolamine, di-isopropanolamine,
N-n-butylmonoethanolamine, N-n-butyldiethanolamine and
diglycolamine.
[0084] Examples of the sulfur-containing compounds include
dimethylsulfoxide, sulfolane and thiodiglycol.
[0085] In an embodiment, a mixture of the water-soluble organic
solvents may be comprised in an ink composition according to the
present invention. The individual organic solvents preferably being
present in an amount of 1 weight % to 50 weight %, more preferably
in an amount of 1 weight % to 40 weight %, even more preferably in
an amount of 1 weight % to 25 weight %, relative to the total ink
composition.
[0086] The total amount of the water-soluble organic solvent
contained in the ink composition is not particularly limited. It
is, however, preferably 1 weight % to 75 weight %, and more
preferably 10 weight % to 70 weight %, and even more preferably 15
weight % to 60 weight % with respect to the total ink composition.
When the amount of the water-soluble organic solvent is more than
80 weight %, the drying times of the ink compositions may be too
long. When the amount is less than 10 weight %, water in the ink
compositions may evaporate more quickly, which may significantly
reduce the stability of the ink composition.
Optional Surfactant
[0087] An ink composition according to the present invention may
optionally comprise one or more surfactant. Examples of surfactants
are not specifically limited. The following can be cited.
[0088] Examples of the surfactant include nonionic surfactants,
cationic surfactants, anionic surfactants, amphoteric surfactants,
in particular betaine surfactants, silicone surfactants, and
fluorochemical surfactants. Particularly, at least one selected
from acetylene surfactants, silicone surfactants and fluorochemical
surfactants capable of reducing the surface tension to 30 mN/m or
lower is preferably used.
[0089] Examples of a cationic surfactant include: aliphatic amine
salts, aliphatic quaternary ammonium salts, benzalkonium salts,
benzethonium chloride, pyridinium salts, imidazolinium salts.
[0090] Examples of an anionic surfactant include: polyoxyethylene
alkylether acetic acid salts, dodecylbenzene sulfonic acid salts,
lauric acid salts, and salts of polyoxyethylene alkylether sulfate,
an aliphatic acid soap, an N-acyl-N-methyl glycin salt, an
N-acyl-N-methyl-.beta.-alanine salt, an N-acylglutamate, an
acylated peptide, an alkylsulfonic acid salt, an
alkylbenzenesulfonic acid salt, an alkylnaphthalenesulfonic acid
salt, a dialkylsulfo succinate (e.g., sodium dioctyl sulfosuccinate
(DSS); alternative names: docusate sodium, Aerosol OT and AOT),
alkylsulfo acetate, .alpha.-olefin sulfonate, N-acyl-methyl
taurine, a sulfonated oil, a higher alcohol sulfate salt, a
secondary higher alcohol sulfate salt, an alkyl ether sulfate, a
secondary higher alcohol ethoxysulfate, a polyoxyethylene
alkylphenyl ether sulfate, a monoglysulfate, an aliphatic acid
alkylolamido sulfate salt, an alkyl ether phosphate salt and an
alkyl phosphate salt. Examples of an amphoteric surfactant include:
a carboxybetaine type, a sulfobetaine type, an aminocarboxylate
salt and an imidazolium betaine.
[0091] Examples of a nonionic surfactant include: polyoxyethylene
alkylether, polyoxypropylene polyoxyethylene alkylether, a
polyoxyethylene secondary alcohol ether, a polyoxyethylene
alkylphenyl ether, a polyoxyethylene sterol ether, a
polyoxyethylenelanolin derivative polyoxyethylene polyoxypropylene
alkyl ether, polyoxyethylene alkylester, a polyoxyethyleneglycerine
aliphatic acid ester, a polyoxyethylene castor oil, a hydrogenated
castor oil, a polyoxyethylene sorbitol aliphatic acid ester, a
polyethylene glycols aliphatic acid ester, an aliphatic acid
monoglyceride, a polyglycerine aliphatic acid ester, a sorbitan
aliphatic acid ester, polyoxyethylene sorbitan aliphatic ester, a
propylene glycol aliphatic acid ester, a cane sugar aliphatic acid
ester, an aliphatic acid alkanol amide, polyoxyethylene alkylamide,
a polyoxyethylene aliphatic acid amide, a polyoxyethylene
alkylamine, an alkylamine oxide, an acetyleneglycol, an ethoxylated
acetylene glycol, acetylene alcohol.
[0092] Examples of the nonionic fluorochemical surfactants include
perfluoroalkyl phosphoric acid ester compounds, perfluoroalkyl
ethylene oxide adducts, and polyoxyalkylene ether polymer compounds
having perfluoroalkyl ether groups as side chains. Among these,
polyoxyalkylene ether polymer compounds having perfluoroalkyl ether
groups as side chains are preferable because they are low in
foaming property.
[0093] As the fluorochemical surfactants, commercially available
products may be used. Examples of the commercially available
products include SURFLON S-HI, S-112, S-113. S-121, S-131, S-132,
S-141 and S-145 (all of which are produced by Asahi Glass Co.,
Ltd.), FLUORAD FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430
and FC-431 (all of which are produced by Sumitomo 3M Limited),
MEGAFAC F-470, F-1405 and F-474 (all of which are produced by
Dainippon Ink Chemical Industries Co., Ltd.), ZONYL TBS, FSP, FSA,
FSN-100, FSN, FSO-100, FSO, FS-300 and UR (all of which are
produced by E. I. du Pont de Nemours and Company), FT-110, FT-250,
FT-251, FT-400S, FT-150 and FT-400SW (all of which are produced by
Neos Company Limited), and POLYFOX PF-136A, PF-156A, PF-151N,
PF-154, and PF-159 (all of which are produced by OMNOVA Solutions
Inc.). Among these, ZONYL FS-300 (produced by E. I. du Pont de
Nemours and Company), FT-110, FT-250, FT-251, FT-400S, FT-150,
FT-400SW (produced by Neos Company Limited), and POLYFOX PF-151N
(produced by OMNOVA Solutions Inc.) are preferable in that they are
excellent in print quality, particularly in color developing
ability and in dye-leveling property.
[0094] The silicone surfactant is not particularly limited and may
be suitably selected in accordance with the intended use.
[0095] Examples of the silicone surfactant include
side-chain-modified polydimethylsiloxane, both-ends-modified
polydimethylsiloxane, one-end-modified polydimethylsiloxane, and
side-chain/both-ends-modified polydimethylsiloxane.
Polyether-modified silicone surfactants having, as a modified
group, a polyoxyethylene group or a polyoxyethylene
polyoxypropylene group are particularly preferable because they
exhibit excellent physical properties as water-based surfactants.
The silicone surfactant may be suitably synthesized or commercial
products may be used. The commercial product is readily available
from BYK Chemie GmbH, Shin-Etsu Chemical Co., Ltd., TORAY Dow
Corning Silicone Co., Ltd., Nihon Emulsion Co., Ltd., Kyoeisha
Chemical Co., Ltd., or the like.
[0096] As the polyether-modified silicone surfactant, commercial
products may be used. Examples of the commercial products include
KF-618, KF-642 and KF-643 (produced by Shin-Etsu Chemical Co.,
Ltd.); EMALEX-SS-5602 and SS-1906EX (produced by Nihon Emulsion
Co., Ltd.); FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163
and FZ-2164 (produced by TORAY Dow Corning Silicone Co., Ltd.); and
BYK-33, BYK 331, BYK 341, BYK 348, BYK 349, BYK 3455, BYK-387
(produced by BYK Chemie GmbH); Tegowet 240, Tegowet 245, Tegowet
250, Tegowet 260 (produced by Evonik); Silwet L-77 (produced by
Sabic).
[0097] In an embodiment, a surfactant may be selected from the
group consisting of dialkyl sulfosucinate salts, such as sodium
dioctyl sulfosuccinate (AOT), ethoxylated acetylene glycols like
Dynol 607 (Air Products) and combinations thereof.
[0098] Specific examples of ethoxylated acetylene glycols are
ethoxylated 3-methyl-1-nonyn-3-ol, ethoxylated
7,10-dimethyl-8-hexadecyne-7,10-diol, ethoxylated
4,7-dimethyl-5-decyne-4,7-diol, ethoxylated
2,4,7,9-tetramethyl-5-decyne-4,7-diol, and ethoxylated
2,5,8,11-tetramethyl-6-dodecyne-5,8-diol. These can be used in
combination with each other.
[0099] All surfactants mentioned in this section may be used
solely, or they may be used in combination of the plural.
Receiving Media
[0100] Suitable receiving media for use in a printing process using
an ink or set of inks (Cyan, Magenta, Yellow and blacK, CMYK)
according to the present invention are not particularly limited to
any type. The receiving medium may be suitably selected depending
on the intended application.
[0101] Suitable receiving media may range from strongly water
absorbing media such as plain paper (for example, Oce Red Label) to
non-water-absorbing media such as plastic sheets (for example, PE,
PP, PVC and PET films). To optimize print quality, inkjet coated
media are known, which media comprise a highly water absorbing
coating.
[0102] Of particular interest in the context of the present
invention are Machine Coated (MC) media (also known as offset
coated media) and glossy (coated) media. MC media are designed for
use in conventional printing processes, for example offset printing
and show good absorption characteristics with respect to solvents
used in inks used in such printing processes, which are usually
organic solvents. MC and glossy media show inferior absorption
behavior with respect to water (worse than plain paper, better than
plastic sheets), and hence aqueous inks.
[0103] Machine coated or offset coated media comprise a base layer
and a coating layer. The base layer may be a sheet of paper mainly
made of wood fibers or a non-woven fabric material comprising wood
fibers combined with synthetic fibers. The base layer may be made
of wood pulp or recycled paper pulp and may be bleached. The base
layer may comprise an internal filler, for example a conventional
white pigment such as precipitated calcium carbonate, heavy calcium
carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate,
titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin
white, aluminum silicate, diatomaceous earth, calcium silicate,
magnesium silicate, synthetic silica, aluminum hydroxide, alumina,
lithophone, zeolite, magnesium carbonate, or magnesium hydrate.
[0104] The base layer may comprise an internal sizing agent used
when producing the base, for example a neutral rosin size used for
neutral papermaking, alkenyl succinic anhydride (ASA), alkyl ketene
dimer (AKD), or a petroleum resin size may be used.
[0105] The thickness of the base is not particularly limited and
may be suitably selected in accordance with the intended use. It
is, however, preferably 50 .mu.m to 300 .mu.m. The basis weight of
the base is preferably 45 g/m.sup.2 to 290 g/m.sup.2.
[0106] The coating layer may comprise a (white) organic and/or
inorganic pigment, a binder and may further contain a surfactant
and other components as required.
[0107] Examples of the inorganic pigment include kaolin, talc,
calcium bicarbonate, light calcium carbonate, calcium sulfite,
amorphous silica, titanium white, magnesium carbonate, titanium
dioxide, aluminum hydroxide, calcium hydroxide, magnesium
hydroxide, zinc hydroxide and chlorite.
[0108] Examples of the organic pigment include (aqueous)
dispersions of, for example, styrene-acrylic copolymer particles,
styrene-butadiene copolymer particles, polystyrene particles or
polyethylene particles.
[0109] The binder preferably comprises an aqueous resin such as
polyvinyl alcohol and polyvinyl alcohol modification products such
as anion-modified polyvinyl alcohol, cation-modified polyvinyl
alcohol or acetal-modified polyvinyl alcohol; polyurethane;
polyvinyl pyrrolidone and polyvinyl pyrrolidone modification
products such as copolymers of polyvinyl pyrrolidone and vinyl
acetate, copolymers of vinyl pyrrolidone and dimethylaminoethyl
methacrylate, copolymers of quaternized vinyl pyrrolidone and
dimethylaminoethyl methacrylate or copolymers of vinyl pyrrolidone
and methacrylamide propyl trimethyl ammonium chloride; celluloses
such as carboxymethyl cellulose, hydroxyethyl cellulose or
hydroxypropyl cellulose; cellulose modification products such as
cationized hydroxyethyl cellulose; synthetic resins such as
polyester, polyacrylic acid (ester), melamine resin or modification
products thereof or copolymers of polyester and polyurethane; and
poly(meth)acrylic acid, poly(meth)acrylamide, oxidized starch,
phosphoric acid-esterified starch, self-modifying starch,
cationized starch, various types of modified starch, polyethylene
oxide, sodium polyacrylate and sodium arginate. These water-soluble
resins may be used alone or in combination.
Printing Process
[0110] A printing process in which the inks according to the
present invention may be suitably used is described with reference
to the appended drawings shown in FIG. 1, FIG. 2A and FIG. 2B.
FIGS. 1, 2A and 2B show schematic representations of an inkjet
printing system (FIG. 1) and inkjet marking device (FIGS. 2A and
2B).
[0111] FIG. 1 shows that a sheet of a receiving medium, in
particular a machine coated medium, P, is transported in a
direction for conveyance as indicated by arrows 50 and 51 and with
the aid of transportation mechanism 12. Transportation mechanism 12
may be a driven belt system comprising one (as shown in FIG. 1) or
more belts. Alternatively, one or more of these belts may be
exchanged for one or more drums. A transportation mechanism may be
suitably configured depending on the requirements (e.g., sheet
registration accuracy) of the sheet transportation in each step of
the printing process and may hence comprise one or more driven
belts and/or one or more drums. For a proper conveyance of the
sheets of receiving medium, the sheets need to be fixed to the
transportation mechanism. The way of fixation is not particularly
limited and may be selected from electrostatic fixation, mechanical
fixation (e.g., clamping) and vacuum fixation. Of these, vacuum
fixation is preferred.
[0112] The printing process as described below comprises of the
following steps: media pretreatment, image formation, drying and
fixing and optionally post treatment.
Media Pretreatment
[0113] To improve the spreading and pinning (i.e., fixation of
pigments and water-dispersed polymer particles) of the ink on the
receiving medium, in particular on slow absorbing media, such as
machine coated media, the receiving medium may be pretreated, i.e.,
treated prior to printing an image on the medium. The pretreatment
step may comprise one or more of the following: [0114] preheating
of the receiving medium to enhance spreading of the used ink on the
receiving medium and/or to enhance absorption of the used ink into
the receiving medium; [0115] primer treatment for increasing the
surface tension of the receiving medium in order to improve the
wettability of the receiving medium by the used ink and to control
the stability of the dispersed solid fraction of the ink
composition (i.e., pigments and dispersed polymer particles).
Primer treatment may be performed in the gas phase, e.g., with
gaseous acids such as hydrochloric acid, sulfuric acid, acetic
acid, phosphoric acid and lactic acid, or in the liquid phase by
coating the receiving medium with a primer solution. The primer
solution may comprise water as a solvent, one or more cosolvents,
additives such as surfactants and at least one compound selected
from a polyvalent metal salt, an acid and a cationic resin; [0116]
corona or plasma treatment.
[0117] FIG. 1 shows that the sheet of receiving medium P may be
conveyed to and passed through a first pretreatment module 13,
which module may comprise a preheater (not shown), for example a
radiation heater, a corona/plasma treatment unit, a gaseous acid
treatment unit or a combination of any of the above. Optionally and
subsequently, a predetermined quantity of the aqueous primer
solution is applied on the surface of the receiving medium P at
aqueous primer solution applying member 14. Specifically, the
aqueous primer solution is provided from storage tank 15 of the
aqueous primer solution to the aqueous primer solution applying
member 14 composed of double rolls 16 and 17. Each surface of the
double rolls 16 and 17 may be covered with a porous resin material
such as sponge. After providing the aqueous primer solution to the
auxiliary roll 16 first, the aqueous primer solution is transferred
to the main roll 17, and a predetermined quantity is applied on the
surface of the receiving medium P. Subsequently, the coated
printing paper P on which the aqueous primer solution was applied
may optionally be heated and dried by drying member 18 which is
composed of a drying heater installed at the downstream position of
the aqueous primer solution applying member 14 in order to decrease
the quantity of the water content in the aqueous primer solution to
a predetermined range. It is preferable to decrease the water
content in an amount of 1.0 weight % to 30 weight % based on the
total water content in the provided primer solution provided on the
receiving medium P.
[0118] To prevent the transportation mechanism 12 from being
contaminated with primer solution, a cleaning unit (not shown) may
be installed and/or the transportation mechanism 12 may be
comprised multiple belts or drums as described above. The latter
measure prevents contamination of the upstream parts of the
transportation mechanism, in particular of the transportation
mechanism in the printing region.
Image Formation
[0119] Image formation is performed in such a manner that,
employing an inkjet printer loaded with inkjet inks, ink droplets
are ejected from the inkjet heads based on the digital signals onto
a print medium.
[0120] Although both single pass inkjet printing and multi pass
(i.e., scanning) inkjet printing may be used for image formation,
single pass inkjet printing is preferably used since it is
effective to perform high-speed printing. Single pass inkjet
printing is an inkjet recording method with which ink droplets are
deposited onto the receiving medium to form all pixels of the image
by a single passage of a receiving medium underneath an inkjet
marking module.
[0121] In FIG. 1, numeral 11 represents an inkjet marking module
comprising four inkjet marking devices, indicated with 111, 112,
113 and 114, each arranged to eject an ink of a different color
(e.g., Cyan, Magenta, Yellow and black). The nozzle pitch of each
head is preferably about 360 dpi. In the present invention, "dpi"
indicates a dot number per 2.54 cm.
[0122] An inkjet marking device for use in single pass inkjet
printing, 111, 112, 113, 114, has a length, L, of at least the
width of the desired printing range, indicated with double arrow
52, the printing range being perpendicular to the media transport
direction, indicated with arrows 50 and 51. The inkjet marking
device may comprise a single print head having a length of at least
the width of said desired printing range. The inkjet marking device
may also be constructed by combining two or more inkjet heads, such
that the combined lengths of the individual inkjet heads cover the
entire width of the printing range. Such a constructed inkjet
marking device is also termed a page wide array (PWA) of print
heads. FIG. 2A shows an inkjet marking device 111 (112, 113, 114
may be identical) comprising 7 individual inkjet heads (201, 202,
203, 204, 205, 206, 207) which are arranged in two parallel rows, a
first row comprising four inkjet heads (201-204) and a second row
comprising three inkjet heads (205-207) which are arranged in a
staggered configuration with respect to the inkjet heads of the
first row. The staggered arrangement provides a page wide array of
nozzles which are substantially equidistant in the length direction
of the inkjet marking device. The staggered configuration may also
provide a redundancy of nozzles in the area where the inkjet heads
of the first row and the second row overlap, see 70 or 80 in FIG.
2B.
[0123] In image formation by ejecting an ink, an inkjet head (i.e.,
print head) employed may be either an on-demand type or a
continuous type inkjet head. As an ink ejection system, there may
be usable either the electric-mechanical conversion system (e.g., a
single-cavity type, a double-cavity type, a bender type, a piston
type, a share mode type, or a shared wall type), or an
electric-thermal conversion system (e.g., a thermal inkjet type, or
a Bubble Jet type (registered trade name)). Among them, it is
preferable to use a piezo type inkjet recording head which has
nozzles of a diameter of 30 .mu.m or less in the current image
forming method.
[0124] FIG. 1 shows that after pretreatment, the receiving medium P
is conveyed to upstream part of the inkjet marking module 11. Then,
image formation is carried out by each color ink ejecting from each
inkjet marking device 111, 112, 113 and 114 arranged so that the
whole width of the receiving medium P is covered.
[0125] Optionally, the image formation may be carried out while the
receiving medium is temperature controlled. For this purpose a
temperature control device 19 may be arranged to control the
temperature of the surface of the transportation mechanism (e.g.
belt or drum) underneath the inkjet marking module 11.
Drying and Fixing
[0126] After an image has been formed on the receiving medium, the
prints have to be dried and the image has to be fixed onto the
receiving medium. Drying comprises the evaporation of solvents, in
particular those solvents that have poor absorption characteristics
with respect to the selected receiving medium.
[0127] FIG. 1 schematically shows a drying and fixing unit 20,
which may comprise a heater (not shown), for example a radiation
heater. After an image has been formed, the print is conveyed to
and passed through the drying and fixing unit 20. The print is
heated such that solvents present in the printed image, to a large
extent water, evaporate. The speed of evaporation and hence drying
may be enhanced by increasing the air refresh rate in the drying
and fixing unit 20. Simultaneously, film formation of the ink
occurs, because the prints are heated to a temperature above the
minimum film formation temperature (MFFT). The residence time of
the print in the drying and fixing unit 20 and the temperature at
which the drying and fixing unit 20 operates are optimized, such
that when the print leaves the drying and fixing unit 20 a dry and
robust print has been obtained. As described above, the
transportation mechanism 12 in the fixing and drying unit 20 may be
separated from the transportation mechanism of the pretreatment and
printing section of the printing apparatus and may comprise a belt
or a drum.
[0128] Hitherto, the printing process was described such that the
image formation step was performed in-line with the pretreatment
step (e.g., application of an aqueous primer solution) and a drying
and fixing step, all performed by the same apparatus (see FIG. 1).
However, the printing process is not restricted to the
above-mentioned embodiment. A method in which two or more machines
are connected through a belt conveyor, drum conveyor or a roller,
and the step of applying an aqueous primer solution, the (optional)
step of drying a coating solution, the step of ejecting an inkjet
ink to form an image and the step or drying an fixing the printed
image are performed. It is, however, preferable to carry out image
formation with the above defined in-line image forming method.
EXAMPLES
Experimental and Measurement Methods
Fusing Experiments
[0129] Fusing experiments are performed with a Ricoh Fuser, model
592 of Ricoh company LTD. The Ricoh fuser comprises a rotatable
drum (fuse drum) having a diameter of 20 cm and a page-wide Halogen
fuse lamp having a power of approximately 750 W. The fuse lamp is
arranged at a position opposite to the fuse drum at a distance of 3
cm. The Ricoh fuser can be operated at settings from 1 to 10. Each
setting corresponds to a rotation speed of the fuse drum. FIG. 3
shows a correlation between the Ricoh fuse setting (x-axis) and the
rotation speed of the fuse drum (y-axis), in revolutions per minute
(RPM). The rotation speed of the fuse drum increases with an
increasing Ricoh fuse setting. The exposure time to fuse radiation
of a sheet of recording medium transported by the fuse drum
decreases with an increasing Ricoh fuse setting, hence the applied
fuse energy decreases with increasing Ricoh fuse setting. All
fusing experiments performed with inks according to the present
invention were performed under the same conditions.
[0130] Directly after fusing an ink image to a sheet of recording
media, the ink layer is rubbed with a piece of plain paper (Oce Red
label). The robustness of the print is judged based on the damage
imparted to the ink layer and valued from 1 to 5, wherein:
5 represents an excellent print robustness: no damage imparted to
the ink layer; 4 represents a good print robustness: some matting
effect of the rubbed area; 3 represents a sufficient print
robustness: minor visual damage imparted to the ink layer; 2
represents a weak print robustness: substantial visual damage
imparted to the ink layer; 1 represents a bad print robustness:
completely removed ink layer after rubbing.
Glass Transition Temperature (T.sub.g)
[0131] The T.sub.g is determined according to ASTM E 1356-03 with
differential scanning calorimetry and measured with a TA
instruments Q2000. The prepared sample was heated at a rate of
10.degree. C./min. The onset of the T.sub.g was determined during a
second run (i.e., sample was heated and cooled first before
starting the measurement). The T.sub.g is a secondary transition
and can be determined by analyzing the deflection point of the DSC
curve.
Minimum Film Forming Temperature (MFFT)
[0132] In the context of the present invention, latex compositions
are selected based on their MFFT as specified by the supplier. The
MFFT can be determined in accordance with ASTM D-2354, for example
on a Sheen Instruments Ltd, MFFT bar SS-3000. The wet latex
composition is cast on a bar or plate (depending on the apparatus
configuration) with a pre-imposed an equilibrated temperature
gradient and dry air flow. The MFFT is determined by visual
observation of the transition point (temperature) at which the
formed film changes from a turbid white and/or cracked film into a
clear and coherent film.
Preparation of Ink Compositions
Comparative Example A
[0133] 170 grams of NeoCryl A-662 latex (obtained from DSM, 40
weight % latex, the latex particles having an average particle
diameter D50 of .+-.100 nm; the latex resin having a T.sub.g of
97.degree. C. and a MFFT >90.degree. C.), 285.7 grams of Pro-Jet
Cyan APD 1000 pigment dispersion (14 weight % pigment dispersion,
obtained from FujiFilm Imaging Colorants), 215 grams of PEG600
(obtained from Sigma Aldrich), 50 grams of 1,2-propanediol
(obtained from Sigma Aldrich), 8.7 grams of Dynol 607 (obtained
from Air Products), 3.5 grams of BYK 348 (obtained from BYK), 3.5
grams of Tegowet 240 (obtained from Sabic) and 263.6 grams of
demineralized water were mixed in a vessel, stirred for
approximately 60 minutes and filtered over a Pall Profile Star
absolute glass filter having a pore size of 1 .mu.m. The obtained
ink composition is shown in Table 1.
[0134] This ink composition was used as a reference for the
drying/curing behavior of the ink compositions comprising an acetal
cosolvent as is demonstrated in examples 1-3.
Comparative Example B
[0135] The working method of Comparative Example A was repeated and
Dipropylene Glycol Mono Methyl Ether (DPGME; obtained from Sigma
Aldrich) was added in an amount of 3 wt % relative to the total ink
composition. To maintain the viscosity of the ink composition
comparable to the reference ink of comparative example A, the
amount of DPGME was compensated for, by reducing the amount of
water. The obtained ink composition is shown in Table 1.
Example 1
[0136] The working method of Comparative Example A was repeated and
2,5,7,10-tetra-oxa-undecane (TOU; manufactured by Lambiotte&Cie
and obtained from ICS) was added in an amount of 3 wt % relative to
the total ink composition. To maintain the viscosity of the ink
composition comparable to the reference ink of comparative example
A, the amount of the acetal (TOU in the present example) was
compensated for, by reducing the amount of water. The obtained ink
composition is shown in Table 1.
Examples 2-3
[0137] Example 1 was repeated. As the acetal cosolvent, TOU was
substituted for Methylal (example 2) and Glycerol formal (example
3), respectively, both manufactured by Lambiote&Cie and
obtained from ICS. The obtained ink compositions are shown in Table
1
Comparative Example C
[0138] The working method of Comparative Example A was repeated
with NeoCryl A-1127 latex (obtained from DSM, 40 weight % latex,
the latex resin having a T.sub.g at -13.degree. C. and at
110.degree. C. and a MFFT of 7.degree. C.) instead of Neocryl A-662
latex. The obtained ink composition is shown in Table 1.
[0139] This ink composition was used as a reference for the
drying/curing behavior of the ink compositions comprising an acetal
cosolvent as is demonstrated in examples 4-6.
Examples 4-6
[0140] The working method of Comparative Example C was repeated and
2,5,7,10-tetra-oxa-undecane (TOU; example 4), Methylal (example 5)
and Glycerol formal (example 6), respectively, were added in an
amount of 3 wt % relative to the total ink composition. To maintain
the viscosity of the ink composition comparable to the reference
ink of comparative example A, the amount of the acetal was
compensated for, by reducing the amount of water. The obtained ink
compositions are shown in Table 1.
Comparative Example D
[0141] The working method of Comparative Example A was repeated
with Carboset PC 27 latex (obtained from Lubrizol) instead of
Neocryl A-662 latex. The Carboset PC 27 latex has a MFFT of about
90.degree. C. The obtained ink composition is shown in Table 1.
[0142] This ink composition was used as a reference for the
drying/curing behavior of the ink compositions comprising an acetal
cosolvent as is demonstrated in example 7.
Example 7
[0143] The working method of Comparative Example D was repeated and
2,5,7,10-tetra-oxa-undecane (TOU) was added in an amount of 3 wt %
relative to the total ink composition. To maintain the viscosity of
the ink composition comparable to the reference ink of comparative
example A, the amount of the acetal was compensated for, by
reducing the amount of water. The obtained ink composition is shown
in Table 1.
TABLE-US-00001 TABLE 1 Ink compositions of comparative examples A-D
and examples 1-7. The amounts are in weight % relative to the total
ink composition. (comparative) examples: compound (A) (B) 1 2 3 (C)
4 5 6 (D) 7 Latex .sup.1) A-662 .sup.2) 6.8 6.8 6.8 6.8 6.8 A-1127
.sup.2) 6.8 6.8 6.8 6.8 PC 27 .sup.3) 6.8 6.8 Pigment .sup.1)4) 4 4
4 4 4 4 4 4 4 4 4 Cosolvents PEG600 21.5 21.5 21.5 21.5 21.5 21.5
21.5 21.5 21.5 21.5 21.5 1,2 5 5 5 5 5 5 5 5 5 5 5 propanediol
DPGME 3 TOU .sup.5) 3 3 3 Methylal .sup.5) 3 3 Glycerol 3 3 formal
.sup.6) surfactants Dynol 607 0.87 0.87 0.87 0.87 0.87 0.87 0.87
0.87 0.87 0.87 0.87 BYK 348 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35
0.35 0.35 0.35 Tegowet 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35
0.35 0.35 240 Water 61.13 58.13 58.13 58.13 58.13 61.13 58.13 58.13
58.13 61.13 58.13 total 100 100 100 100 100 100 100 100 100 100 100
.sup.1) The amount of latex and pigment is the amount of solids
relative to the total ink composition .sup.2) DSM Neocryl series
.sup.3) Lubrizol Carboset PC 27 latex .sup.4) Pro-jet Cyan APD 1000
pigment (FujiFilm Imaging Colorants) .sup.6) Acetal cosolvents
according to the present invention
Evaluation of Fuse Behavior/(Fuse) Energy Consumption
Example 8
[0144] The inks according to comparative examples A-D and examples
1-7 were applied to machine coated media Hello Gloss (115
g/m.sup.2) obtained from Hello, by rod coating an ink layer having
a thickness of 8 .mu.m. The wet rod coat samples were subjected to
the Ricoh fuser as described above and treated at fuse settings of
4, 4.5, 5 and 5.5 corresponding to fuse drum rotational speeds of
20 RPM, 25 RPM, 30 RPM and 35 RPM, respectively.
[0145] The robustness of the ink layer on the substrate were
determined according to the method as described above.
[0146] The results of this evaluation are summarized in Table
2.
TABLE-US-00002 TABLE 2 Results robustness.sup.4) Print Print Print
Print robustness robustness robustness robustness at Ricoh at Ricoh
at Ricoh at Ricoh fuse fuse fuse fuse (comparative) additional
setting setting setting setting example latex cosolvent.sup.1) 4
4.5 5 5.5 (A) A-662 .sup.3) -- 5 2 1 1 (B) A-662 .sup.3) DPGME 5 4
3 2 1 A-662 .sup.3) TOU 5 5 5 4 2 A-662 .sup.3) Methylal 5 4 3 2 3
A-662 .sup.3) Glycerol 5 4 3 2 formal (C) A-1127 .sup.3) -- 3 3 2 2
4 A-1127 .sup.3) TOU 3 3 2 2 5 A-1127 .sup.3) Methylal 3 3 2 2 6
A-1127 .sup.3) Glycerol 3 3 2 2 formal (D) PC 27 .sup.4) -- n.d.
.sup.2) 2 2 1 7 PC 27 .sup.4) TOU n.d. .sup.2) 5 5 4 .sup.1)All ink
compositions comprised PEG600 (21.5 wt %) and 1,2-propanediol (5 wt
%) as cosolvents .sup.2) not determined .sup.3) DSM Neocryl series
.sup.4) Lubrizol Carboset series .sup.4) Print robustness is rated
from 1 to 5, wherein: 5 represents an excellent print robustness:
no damage imparted to the ink layer; 4 represents a good print
robustness: some matting effect of the rubbed area; 3 represents a
sufficient print robustness: minor visual damage imparted to the
ink layer; 2 represents a weak print robustness: substantial visual
damage imparted to the ink layer; 1 represents a bad print
robustness: completely removed ink layer after rubbing.
[0147] Table 2 shows that by adding an acetal cosolvent to an ink
composition comprising a relatively high MFFT latex composition
(compare examples 1-3 with comparative example A and example 7 with
comparative example D) the required fuse energy for obtaining a
robust ink layer, significantly reduces (i.e., at a lower fuse
energy (higher Ricoh fuse setting) the print robustness in examples
1-3 is higher than the robustness in comparative example A).
[0148] At fuse settings 4.5 and 5 (corresponding to a rotational
speed of the fuse drum of 25 RPM and 30 RPM, respectively) there
are subtle differences in robustness level among the ink
compositions according to examples 1-3 (e.g. comprising an acetal
cosolvent) and comparative example B (comprising DPGME). The order
of the robustness of the rod coat samples fused at said settings is
as follows:
Example 1 (TOU)>>Comparative Example B (DPGME)>Example 3
(glycerol formal)>Example 2 (methylal)
[0149] Overall it can be concluded that the ink compositions
comprising an acetal cosolvent show a robustness level comparable
to the robustness level of an ink comprising DPGME and that in
particular TOU shows an improved robustness level.
[0150] Table 2 also shows that by adding an acetal cosolvent to an
ink composition comprising a relatively low MFFT latex composition
(compare examples 4-6 with comparative example C, there is no
significant influence on the robustness and no fuse energy gain is
obtained. The glass transition temperature/MFFT of the latex
composition seems to be dominant in the final robustness and fuse
energy consumption. However, the presence of the acetal cosolvent
in the ink compositions do not disturb the formed film in the sense
that it becomes tacky or rough.
[0151] Detailed embodiments of the present invention are disclosed
herein; however, it is to be understood that the disclosed
embodiments are merely exemplary of the invention, which can be
embodied in various forms. Therefore, specific structural and
functional details disclosed herein are not to be interpreted as
limiting, but merely as a basis for the claims and as a
representative basis for teaching one skilled in the art to
variously employ the present invention in virtually and
appropriately detailed structure. In particular, features presented
and described in separate dependent claims may be applied in
combination and any combination of such claims are herewith
disclosed. Further, the terms and phrases used herein are not
intended to be limiting; but rather, to provide an understandable
description of the invention. The terms "a" or "an", as used
herein, are defined as one or more than one. The term "combination
of the plural", as used herein, is defined as two or more than
two.
* * * * *